Martin F. McCarthy, S.J., astronomer at the Vatican Observatory from 1958 until his retirement in 1999, died peacefully on 5 February at the age of 86 years at the Jesuit Campion Health Center in Weston, Massachusetts where he had resided since his retirement. McCarthy received his doctorate in astronomy from Georgetown University, Washington, DC in 1951. The study of carbon stars, stars whose atmospheres contain more carbon than oxygen, was a major interest for McCarthy. Carbon stars were originally discovered and studied in the 1860s by Fr. Secchi, the eminent Jesuit astronomer. Interestingly, Fr. Secchi spent 1848-50 at Georgetown University in Washington, where Martin McCarthy would receive his PhD degree 101 years later. Upon completion of his seminary studies in theology, he carried out post-doctoral research at Warner and Swasey Observatory, Lick Observatory, the Dominion Astrophysical Observatory and Yerkes Observatory until he began his career at the Vatican Observatory where he served as a key figure in the Observatory’s transition to the world of modern research. He also brought the Observatory onto the international stage through his collaborations in research at, among other institutes, Palomar Observatory, Lowell Observatory, Las Campanas Observatories, the Cerro Tololo Interamerican Observatory and the Carnegie Institute of Washington. He served on the Executive Council of the Italian Astronomical Society (1969-1971), was chair of the National Committee of the Vatican to the International Astronomical Union (IAU) from 1979 until his retirement and was President of IAU Commission 25 Stellar Photometry and Polarimetry (1976-1979). During his career he published more than 120 research papers. He was a natural teacher, who enjoyed explaining and talking science to students and visitors. Among his many contributions to the growth of the Vatican Observatory, he was responsible in 1986 for the beginning of the series of the Vatican Observatory Summer Schools in Astrophysics, an initiative which has become world renowned. It was this interest, and his concerns for students who had limited opportunities to study science, that led him to suggest the summer astronomy program.